CH.3 Network Media

[3.1] What is bounded media?

A physical transmission medium / such as copper or fiber cable.

[3.1] Bandwidth versus throughput?

Bandwidth is capacity. throughput is the actual achieved data-transfer rate.

[3.1] What is attenuation?

A signal's loss of strength as it travels.

[3.1] What is electromagnetic interference (EMI)?

Unwanted electromagnetic energy that disrupts electrical communication signals.

[3.1] What is crosstalk?

Interference caused by signals coupling between wire pairs or nearby circuits.

[3.1] Which common network medium resists EMI?

Fiber-optic cable / because it transmits light rather than electrical signals.

[3.1] Why can a 1 Gbps link deliver much less than 1 Gbps of useful traffic?

Congestion / protocol overhead / errors / and bottlenecks can reduce throughput.

[3.2] What is coaxial cable?

A cable with a central conductor / insulation / and a surrounding conductive shield.

[3.2] What is twinaxial cable?

A shielded cable with two inner conductors / commonly used in short equipment interconnects.

[3.2] What is a DAC cable?

Direct attach copper: a short copper interconnect with compatible transceiver-style ends / often used within or between racks.

[3.2] What does DOCSIS support?

Data communication over cable-television provider infrastructure.

[3.2] What is an F-type connector commonly used for?

Coaxial connections for cable television and cable internet.

[3.2] What is a BNC connector associated with?

Coaxial connections using a bayonet-style coupling.

[3.2] RG-6 versus RG-11?

Both are coaxial types. RG-11 generally has lower loss for longer runs but is thicker and less flexible.

[3.3] Why are copper wire pairs twisted?

To reduce interference and crosstalk.

[3.3] UTP versus shielded twisted pair?

UTP lacks added shielding. shielded cable uses conductive shielding to reduce interference when properly installed.

[3.3] What connector is commonly used for twisted-pair Ethernet?

RJ45 / commonly referring to the 8-position Ethernet connector.

[3.3] What connector is commonly associated with telephone wiring?

RJ11.

[3.3] What does T568A or T568B specify?

The wire-to-pin arrangement for terminating twisted-pair cabling.

[3.3] What is the T568B pin order from 1 to 8?

White/orange / orange / white/green / blue / white/blue / green / white/brown / brown.

[3.3] What changes between T568A and T568B?

The green and orange pairs exchange positions. the blue and brown pairs remain in the same positions.

[3.3] What is a straight-through Ethernet cable?

A cable using the same wiring arrangement at both ends.

[3.3] What is a traditional crossover cable?

A cable with transmit and receive pairs crossed / commonly made with T568A at one end and T568B at the other.

[3.3] What is Auto-MDI-X?

A feature that automatically adjusts transmit/receive pairing / reducing the need for crossover cables.

[3.3] What does 1000BASE-T identify?

1 Gbps baseband Ethernet over twisted-pair copper.

[3.3] What does 10GBASE-T identify?

10 Gbps Ethernet over suitable twisted-pair copper.

[3.3] What is the common maximum channel length for Cat5e Gigabit Ethernet?

100 meters / typically including a 90-meter permanent link plus patch cords.

[3.3] Cat5e versus Cat6a for common Ethernet use?

Cat5e commonly supports 1 Gbps at 100 m. Cat6a supports 10 Gbps at 100 m.

[3.3] Does Cat6 always support 10 Gbps at 100 meters?

No. Cat6 supports 10 Gbps over shorter distances depending on installation. Cat6a is designed for 10 Gbps at 100 m.

[3.4] Single-mode versus multimode fiber?

Single-mode has a smaller core and generally supports longer links. multimode has a larger core and is commonly used for shorter links.

[3.4] What limits the reach of a fiber link?

The Ethernet standard / transceiver specifications / fiber type / optical loss / and installation quality.

[3.4] Does single-mode fiber have one universal maximum distance?

No. Reach varies with the optics / standard / and link loss budget.

[3.4] What are LC / SC / and ST?

Common fiber-optic connector types.

[3.4] What is an MPO connector?

A multifiber connector used for high-density fiber links.

[3.4] What does 10GBASE-SR commonly use?

Short-reach 10 Gbps Ethernet optics over multimode fiber.

[3.4] What does 10GBASE-LR commonly use?

Long-reach 10 Gbps Ethernet optics over single-mode fiber.

[3.4] What is wavelength-division multiplexing (WDM)?

Carrying multiple optical channels over fiber using different wavelengths of light.

[3.5] What is an MDF?

Main distribution frame: the principal network distribution location serving a facility.

[3.5] What is an IDF?

Intermediate distribution frame: a distribution location serving a floor or area and connecting back toward the MDF.

[3.5] What does a patch panel do?

Organizes and terminates cabling. it does not perform packet switching.

[3.5] What does a punchdown tool do?

Seats and trims wires into compatible insulation-displacement terminals.

[3.5] What does a cable crimper do?

Attaches compatible modular connectors to cable ends.

[3.5] What does a wire-map cable tester check?

Conductor continuity and pin relationships / including opens / shorts / and miswiring. capabilities vary by tester.

[3.5] What does an optical power meter measure?

Received optical power on a fiber link.

[3.5] What does an OTDR help locate?

Fiber events or faults by analyzing reflections and backscatter from light pulses.

[3.6-3.9] A copper link near motors has errors. What should you investigate?

EMI / cable routing / shielding/grounding where applicable / and whether fiber would suit the link better.

[3.6-3.9] A duplex fiber link has no connection after installation. What should you check?

TX/RX alignment / connector cleanliness / optic compatibility / fiber type / and received optical power.

[Extra: N10-009] What is plenum-rated cable?

Cable rated for use in environmental air-handling spaces under applicable requirements / with restricted flame and smoke characteristics.

[Extra: N10-009] What are SFP and QSFP?

Pluggable transceiver form factors. match the module's speed / protocol / wavelength / medium / and device compatibility to the link